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Objectives

70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network, Enhanced Chapter 7: Planning a DNS Strategy. Objectives. Describe the functions of the Domain Name System Choose a DNS namespace strategy Install DNS Explain the function of DNS zones

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Objectives

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  1. 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network, EnhancedChapter 7: Planning a DNS Strategy

  2. Objectives • Describe the functions of the Domain Name System • Choose a DNS namespace strategy • Install DNS • Explain the function of DNS zones • Integrate Active Directory and DNS, including Dynamic DNS • Integrate DNS with WINS 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  3. Functions of the Domain Name System • DNS is used to resolve host names to IP addresses and find services • DNS is an essential service for a network that uses Active Directory • DNS is also required if you want resources such as Web servers available on the Internet • The most common operating system DNS is implemented on is UNIX/Linux, and this can be integrated with the Windows version of DNS 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  4. Host Name Resolution • Host names are used because they are easier to remember than IP addresses • When a program uses a host name, the host name must be converted to an IP address before the resource can be contacted 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  5. Host Name Resolution (continued) • The contents of a hosts file are a list of IP addresses and host names • The steps followed by Windows Server 2003 to resolve host names are: • Host name is checked • Hosts file is loaded into cache • DNS cache is searched • DNS server is queried 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  6. Host Name Resolution (continued) 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  7. Activity 7-1: Configuring a Hosts File • The purpose of this activity is to configure and test a hosts file 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  8. Forward Lookup • When a DNS server resolves a host name to an IP address it is known as forward lookup • Resolving host names within an organization is a two-packet process • In recursive lookup a DNS query that is resolved through other DNS servers until the requested information is located 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  9. Forward Lookup (continued) 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  10. Registering a Domain Name • To participate in the worldwide DNS lookup system, you must register your domain name with a registrar • A top-level domain (TLD) name is the highest level of domain in the DNS system • A registrar is an organization that puts domain information into the top-level domain DNS servers so that your domain will be integrated with the worldwide DNS system 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  11. Registering a Domain Name (continued) 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  12. Reverse Lookup • When DNS is used to resolve IP addresses to host names, the process is known as reverse lookup • A reverse lookup allows you to specify an IP address and the DNS server returns the host name that is defined for it 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  13. DNS Record Types • DNS records are created on a DNS server to resolve queries • Each type of record holds different information about a service, host name, IP address, or domain • Different queries request information contained in specific DNS record types 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  14. DNS and BIND • Berkeley Internet Name Domain (BIND) is a version of DNS that runs on UNIX/Linux • It is the de facto standard for DNS implementation and many other implementations of DNS reference BIND version numbers for feature compatibility 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  15. DNS Namespace Strategies • DNS namespace can be broken into external and internal DNS • External DNS is used to hold records for Internet resources, such as company Web servers and e-mail servers • Internal DNS is used to hold records for internal resources, such as Active Directory and internal Web applications 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  16. DNS Namespace Strategies (continued) • To maintain security, the servers holding internal and external DNS records must remain separate • The three options for utilizing DNS namespaces in Windows Server 2003 are as follows: • Use the existing external namespace • Use a delegated subdomain of the external namespace • Use a separate unique namespace 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  17. Using the Existing External Namespace • Using the existing external namespace has some disadvantages: • It is awkward to synchronize DNS records between the internal and external DNS servers because no automated mechanism can be used (not recommended) • The automated synchronization mechanisms synchronize all DNS records between two DNS servers, not just the appropriate records; this results in internal DNS records being available on the external DNS servers (security risk) 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  18. Using the Existing External Namespace (continued) • The records for external resources must be manually added to the internal DNS servers • If not, users cannot resolve the names of external resources properly 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  19. Using a Delegated Subdomain of the External Namespace • A delegated subdomain: • Has been configured as its own zone so that it can be placed on DNS servers independently of the parent domain • Allows you to keep separate DNS servers for internal and external resources with no need to synchronize records 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  20. Using a Separate Unique Namespace • Do not use a domain name for your internal namespace if it has already been registered for use on the Internet • You should register the internal namespace you choose, if possible • You can also choose a domain name that is not even possible to use on the Internet 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  21. Installing DNS • Windows Server 2003 can act as a DNS server • Can install DNS on multiple servers and you must add DNS individually to each of these servers • To reduce WAN traffic in large organizations, DNS servers can be placed in each physical location • To decide the best placement of DNS servers during the planning process, estimate the amount of traffic that will be generated by DNS 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  22. Activity 7-2: Installing DNS • The purpose of this activity is to install DNS on your server and confirm it is running 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  23. DNS Zones • A DNS zone is the part of the DNS namespace for which a DNS server is responsible • Once inside the zone, you can create DNS records and subdomains • When a zone is created, you designate whether it will hold records for forward lookups or reverse lookups • Forward lookup zone: holds records for forward lookups • Reverse lookup zone: holds records for reverse lookups 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  24. Primary and Secondary Zones • Primary and secondary zones are used to synchronize DNS information automatically between DNS servers • A primary zone is the first to be created, and all of the DNS records are created in the primary zone • A secondary zone takes copies of primary zone information • You cannot directly edit the records in a secondary zone because they are copied from the primary zone • The process of moving information from the primary zone to the secondary zone is called a zone transfer 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  25. Activity 7-3: Creating a Primary Zone • The purpose of this activity is to create a primary zone to hold resource records 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  26. Activity 7-4: Creating a Secondary Zone • The purpose of this activity is to create a local copy of DNS information using a secondary zone 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  27. Active Directory Integrated Zones • An Active Directory integrated zone stores information in Active Directory rather than in a file on the local hard drive • To store DNS information in an Active Directory integrated zone, the DNS server must also be a domain controller 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  28. Active Directory Integrated Zones (continued) • Storing DNS information in Active Directory offers the following advantages over traditional primary and secondary zones: • Automatic backup of zone information • Multimaster replication • Increased security 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  29. DNS Zone Storage in Active Directory • Two areas in Active Directory can be used to store DNS zones: • Domain directory partition • Application directory partition • The domain directory partition of Active Directory holds information specific to a particular Active Directory domain • This partition is replicated to all domain controllers in an Active Directory domain • The information in this partition cannot be replicated to domain controllers in other Active Directory domains 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  30. DNS Zone Storage in Active Directory (continued) • Application directory partitions allow information to be stored in Active Directory but be replicated only among a defined set of domain controllers 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  31. Activity 7-5: Promoting a Member Server to a Domain Controller • The purpose of this activity is to promote a member server to a domain controller 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  32. Activity 7-6: Creating an Active Directory Integrated Zone • The purpose of this activity is to create an Active Directory integrated zone 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  33. Integrating Active Directory Integrated Zones with Traditional DNS • Active Directory integrated zones interact with traditional zones by acting as a primary zone to traditional secondary zones 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  34. Stub Zones • A stub zone is a DNS zone that holds only NS records for a domain • NS records define the name servers that are responsible for a domain 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  35. Stub Zones (continued) 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  36. Activity 7-7: Removing Active Directory Integrated Zones • The purpose of this activity is to remove an Active Directory integrated zone 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  37. Activity 7-8: Creating a Stub Zone • The purpose of this activity is to create a stub zone to direct recursive queries 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  38. Active Directory and DNS • Active Directory requires DNS to function properly • The most important function that DNS performs for Active Directory is locating services, such as domain controllers 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  39. Dynamic DNS • Dynamic DNS is a system in which records can be updated on a DNS server automatically rather than forcing an administrator to create records manually 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  40. Activity 7-9: Testing Dynamic DNS • The purpose of this activity is to verify that a computer is registering a host name using Dynamic DNS 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  41. Dynamic DNS and DHCP • The Dynamic DNS information updated by Windows 2000/XP is negotiated with the DHCP server during the lease process • By default, a DHCP server running on Windows Server 2003 updates DNS records only for Windows 2000/XP clients and only if requested to do so 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  42. WINS Integration • To integrate with WINS, a DNS zone can be configured with a WINS server to help resolve names • If a DNS zone receives a query for a host name for which it has no A record, it forwards the request to a WINS server • This results in slower response times and increased processor utilization 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  43. WINS Integration (continued) • If DNS and WINS are running on separate servers, it also results in increased network traffic and even slower response times • Integrating a WINS server with a DNS forward lookup zone creates a WINS record in the zone • You can specify that records resolved via WINS are not replicated to other DNS servers by selecting the Do not replicate this record check box 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  44. WINS Integration (continued) • Can configure timeout intervals with the Advanced button on the WINS tab in the properties of a zone • The Cache time-out controls how long DNS servers and DNS clients cache this record after it is resolved • The Lookup time-out controls how long the DNS server waits for a response from WINS before sending an error to the requesting client 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  45. Summary • DNS is used to resolve host names to IP addresses and find services • Host name resolution is performed in four steps • Forward lookup resolves host names to IP addresses • Reverse lookup resolves an IP address to a host name • Recursive lookup is performed when a local DNS server queries the root servers on the Internet on behalf of a DNS client 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  46. Summary (continued) • DNS records are created on a DNS server to resolve queries • Each type of DNS record holds different information about a service, host name, IP address, or domain • A DNS zone holds records for a portion of the DNS namespace • Active Directory integrated zones are stored in Active Directory • Active Directory integrated zones can act as primary zones to secondary zones 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

  47. Summary (continued) • A stub zone contains name server records that are used for recursive lookups • Dynamic DNS allows records to be automatically updated on a DNS server • A WINS server can be used to help resolve host names if a DNS server does not have a record that matches a query 70-293: MCSE Guide to Planning a Microsoft Windows Server 2003 Network

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